1. Field of the Invention
This invention relates to a new and improved method for manufacturing spark plugs used in internal combustion engines. More particularly, it refers to a method of attaching a ground electrode to a spark plug base. One such embodiment includes a ring or ring segment internal opening concentrically disposed with respect to a center electrode onto a metal housing of the spark plug. An additional embodiment includes a ring or ring segment internal opening concentrically disposed with respect to a center electrode containing various precious metals on the firing surfaces onto a metal housing of the spark plug.
2. Description of the Prior Art
Commercial internal combustion engine spark plugs in current widespread use have characteristically had a center electrode with an exposed end in its base that is spaced apart from a ground electrode. The ground electrode is usually an "L" shaped single arm welded to an edge of the plug and bent over towards the center electrode at substantially a right angle. Although these plugs perform their intended function, it has been determined that their design substantially detracts from a complete burn Otto cycle in an internal combustion engine's combustion chamber and results in the overheating of the plug parts, incomplete combustion and the production of oxides of nitrogen in the combustion chamber.
Spark plugs are a critical component in an internal combustion engine to assure proper engine performance. Spark plugs include a metal housing which is threaded for installation into the engine, a ground electrode extending from the housing, an insulator (usually manufactured of a ceramic material) carried by the housing, with a center electrode within the insulator, on end of which projects from the end of the insulator and defines a pre-determined gap with the ground electrode. When the spark plug is fired, the spark is generated across the gap. More recently, spark plugs have been designed with a fine wire tip made of a noble metal (platinum or platinum alloy) that has significantly improved engine performance and significantly increased spark plug life. Platinum fine wire spark plugs improve cold starting, acceleration and fuel economy of the engine, as compared to spark plugs not having a platinum firing tip and have a service life of up to 100,000 miles.
Improvements on the design of the ground electrode include U.S. Pat. Nos. 5,280,214, 5,430,346 and U.S. Pat. No. 4,268,774, all incorporated herein by reference. In a preferred embodiment of these ground electrodes, a ring shaped firing surface is attached to an end of one or more integral mounting posts. Each integral mounting post is attached at a second end to a mounting ring. The mounting ring is then seated onto a mounting surface at the bottom end of a spark plug. The known methods of attaching these ground electrodes to the bottom end of the spark plug include eliminating the mounting ring and tack welding the second end of the mounting post directly to an edge of the bottom end of the spark plug, or a plurality of metal surfaces extending above the shoulder on the bottom end of the spark plug are bent over to crimp the mounting ring to secure it to the bottom end. These methods of manufacture have proved to be time consuming, costly and have resulted in poor efficiency and reduction in useful life of the spark plug, as opposed to its potential for being an integral, important means by which internal optimum combustion engine efficiency and output can be attained.